Copper replenishment for copper plating with insoluble anode

ABSTRACT

In one embodiment, the present invention generally provides an apparatus and method for dispersing a chemical reagent into a plating solution. The apparatus generally includes a tank for containing the plating solution and a horizontal vessel in fluid communication with the tank, wherein the horizontal vessel has an input and an output. The apparatus further includes at least one shelf contained inside the horizontal vessel, wherein the at least one shelf extends between the input and the output and the chemical reagent rests on the at least one shelf. In another embodiment, the present invention generally provides an apparatus for dispersing a chemical reagent to a plating solution comprising a tank for containing the plating solution and a vertical vessel in fluid communication with the tank. A lower portion of the vertical vessel includes an inlet and an injector port and an upper portion of the vertical vessel includes an outlet and a manifold. The chemical reagent is positioned between the inlet and the outlet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to a metal platingapparatus and process, namely for the replenishment of chemicalcomponents used to electroplate copper.

2. Description of the Related Art

Semiconductor substrates can be plated with copper by electroplating orelectroless plating processes. During the electroplating, an anode isusually placed into an electrolyte solution and the substrate isconductively coupled to a cathode. As current flows, dissolved copperions from the electrolyte solution are reduced and plated (or deposited)on the surface of the substrate as copper metal. Traditionally, theanode is made from consumable copper metal and is continuously oxidizedto provide copper ions to the plating process. Due to the consumption ofthe copper anode, the dimension of the copper anode is changed.Therefore the directional electrical fields produced by the anode alsochange accordingly. This alteration in the electric field presents achallenge to precisely control the electroplating process, especiallywithin vias with high aspect ratios.

Another electroplating process utilizes an inert or stable anode inplace of a consumable anode. The use of an inert anode providesexcellent control for precision plating since the anode is not consumedduring the plating process. However, the inert anode does not supply asource of copper into the electrolyte solution. As the copper ions arereduced and plated from the electrolyte solution to the substratesurface, the copper ion concentration in the electrolyte solution isdiminished. Therefore, as the plating process progresses, a coppersource, namely copper ions, must be added to the electrolyte solution inorder to continue the plating process. Copper sources are generallychosen from a variety of copper salts that include copper sulfate,copper hydroxide, copper oxide and copper phosphate.

U.S. Pat. No. 5,516,414 teaches a method to maintain an alkaline copperplating solution with a desired concentration of copper ions andhydroxide ions. The '414 patent discloses adding copper hydroxide powderfrom a conduit to an alkaline, pyrophosphate solution in a dissolvingtank. Once the solution has been heated and agitated to insure that thecopper hydroxide has been dissolved, the pyrophosphate solution istransferred via a pump to the plating solution. The plating solution ismonitored with a meter and maintained with a basic pH between 7 and 10by adding the alkaline, pyrophosphate solution. Though the addition ofcopper hydroxide powder is adequate in the realm of electroplatingwires, this technique is unacceptable in a clean environment, such as asemiconductor fabrication room equipped to plate substrates. The dumpingof a powdery precursor into a solution would present contaminationissues for semiconductor processing in a cleanroom environment.

U.S. Pat. No. 5,997,712 realizes the shortcomings of the '414 patent asapplied to a cleanroom. The '712 patent avoids dumping the powderyprecursor and teaches a method to replenish copper ions in a platingsolution with the apparatus depicted in FIG. 1A. The anolyte flows fromthe top of canister 2, through a porous cartridge 4 and into a hollowcavity 6 before flowing out the bottom of canister 2. The cartridge 4includes a filter element that encompasses the powdery copper source.Therefore, the anolyte flows through the canister 2 and is enriched bycopper ions via absorbing the copper source.

However, as illustrated in FIG. 1B, the anolyte can flow into cartridge4 and form different phases of anolyte/copper source. The depletedanolyte 8 enters the cartridge 4 from above and flows downwardly to forma suspension 9 of anolyte/copper source. As the suspension 9 flowstowards the bottom of the cartridge 4, the suspension densifies, forminga viscous cake 10 at the bottom of the cartridge 4. Throughout theformation of cake 10, the flow of anolyte lessens and copper ions ceaseto be consistently replenished in the anolyte. Therefore, longer platetimes reduce substrate throughput with this decrease of the copperconcentration. Also, in the case when copper hydroxide is used as acopper source, the reduction in the hydroxyl ion addition lowers the pHof the anolyte.

Therefore, there is a need for an apparatus and method to replenishchemical compounds within an electrolyte solution in a consistent andreliable manner.

SUMMARY OF THE INVENTION

In one embodiment, the invention generally provides an apparatus fordispersing chemical reagents to a plating solution including a tank forcontaining the plating solution and a cartridge in fluid communicationwith the tank, wherein the cartridge has an input and an output. Theapparatus further includes at least one shelf contained inside thecartridge. The at least one shelf may be impermeable and may extendbetween the input and the output such that the chemical reagent rests onthe at least one shelf.

In another embodiment, the invention generally provides an apparatus fordispersing a chemical reagent to a plating solution comprising a tankfor containing the plating solution and a vertical cartridge in fluidcommunication with the tank. A lower portion of the vertical cartridgeincludes an inlet and an injector port and an upper portion of thevertical cartridge includes an outlet and a manifold. The chemicalreagent is positioned between the inlet and the outlet.

In another embodiment, the invention generally provides a method fordispersing a chemical reagent to a plating solution including flowingthe plating solution from a tank through an input of a cartridge,wherein the cartridge comprises a chemical reagent disposed on at leastone shelf. The plating solution flows across the chemical reagent toenrich the plating solution with the chemical reagent, whereas thechemical agent is dissolved or suspended within the plating solution.The enriched plating solution flows from the cartridge through an outputto the tank.

In another embodiment, the invention generally provides a method formonitoring and controlling a pH setting of a plating solution in a tankincluding determining a pH of the plating solution with a pH meter,transferring an aliquot of the plating solution to a vessel andpressurizing the vessel with a gas to transfer the aliquot to acartridge. The cartridge includes an injector, a chemical reagent and amanifold. The aliquot passes through the injector, which enriches thealiquot with a portion of the chemical reagent and the enriched aliquottransfers through the manifold to the plating solution in the tank. Asecond pH of the plating solution is determined with the pH meter andcompared with the pH setting. Enriched aliquots are transferredrepeatedly to the plating solution until the second pH is equivalent tothe pH setting.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIGS. 1A-B show a cartridge inside a canister as used in the relatedart;

FIG. 2 shows a flow diagram for a two-sectional electrochemical cellwith catolyte and anolyte;

FIG. 3 shows a longitude sectional view of a cartridge with horizontalshelves;

FIGS. 4A-C show cross-sectional views of cartridges with a variety ofshelves;

FIGS. 5A-C show cartridge placements into an anolyte loop;

FIG. 6A shows a vertical sectional view of a cartridge with a bottominjector;

FIG. 6B shows a fragmentary vertical sectional view of a portion of theembodiment of FIG. 6A;

FIG. 7 shows a schematic diagram of a plating system incorporating oneembodiment of a cartridge with a bottom injector;

FIG. 8 is a diagram illustrating the timing sequence of valve operationduring a plating process;

FIG. 9 shows another embodiment of a cartridge with a bottom injectorincorporated into a plating system; and

FIGS. 10A-B show embodiments of injector systems including rotatablecups.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention comprises apparatuses and methods to replenishchemical compounds in plating solutions in a consistent and reliablemanner. The present invention overcomes the shortcomings of the relatedart as described in the background and illustrated in FIG. 1, mainly, bynot blocking anolyte flow with cake formations. Therefore, by utilizingthe various embodiments of the apparatuses and methods of the presentinvention, each substrate experiences more consistent plating times andanolyte chemical concentrations.

Embodiments of the present invention are useful in a variety of platingsystems, including electroplating and electroless plating systems.Further, various embodiments are also applicable to electroplating withsoluble anodes and with insoluble anodes. FIG. 2 shows a schematicarrangement of an electroplating system with a cell 11 containing aninsoluble anode 12. The insoluble anode 12 is made from relatively inertmaterials, such as platinum, titanium, titanium with a Pt-coating,palladium, nickel, stainless steel and/or carbon. The material of theinsoluble anode 12 is generally configured to withstand the variousprocess conditions involved while plating to a wafer or substrate 14.Process conditions may have acidic or basic pH, oxidative/reductivepotentials and an assortment of chemical compounds throughout thesolution. In one embodiment, the insoluble anode 12 endures processconditions such as acidic plating solutions and an oxidative potential.The substrate 14 is attached to the cathode 13, usually by a contactring, pins, and the like (not pictured).

The insoluble anode 12 and the cathode 13 are separated by a membrane 16extending through cell 11. The membrane 16 is an electroconductivemembrane, such as an ion-exchange membrane, nano-filtration membrane,ultra-filtration membrane and others known in the art. The portion ofthe cell 11 containing the cathode 13 is in fluid communication with thecatolyte tank 17 to recirculate the catolyte within. The catolyte is amixture of compounds that may include, for copper plating, sulfuriccopper plating electrolyte or pyrophosphoric copper plating electrolyte.A sulfuric copper plating electrolyte will generally include a mixtureof copper sulfate, sulfuric acid and various organic and inorganicadditives including suppressors, accelerators, levelers and brighteners.Catolyte may pass through a diffuser 15 and be more evenly distributedwhile flowing to the substrate 14.

The portion of the cell 11 containing the insoluble anode 12 is in fluidcommunication with the anolyte tank 18 and recirculates the anolytewithin. For copper plating, the anolyte is a solution containing copperions, often derived from dissolved copper salts, such as copper sulfate.Other copper ion sources include copper hydroxide, copper carbonate,copper oxide and copper phosphate.

Under copper plating electrolysis, the half reaction in scheme (i)occurs on the insoluble anode 12:H₂O→2H⁺+2e⁻+½O_(2(g)),   (i)while Cu²⁺ ions migrate through the membrane 16 from the anolyte to thecatolyte and are reduced according to the half reaction shown in scheme(ii):Cu²⁺+(SO₄)²⁻+2e−→Cu⁰+(SO₄)²⁻.   (ii)The combined half reactions are represented in reaction scheme (iii):CuSO₄+H₂O→Cu⁰+H₂SO₄+½O_(2(g))   (iii)Therefore, as the electroplating process proceeds, the anolyte becomesdepleted of copper ions due to the precipitation of metallic copper aswell as more acidic due to the production of sulfuric acid. Also, wateris consumed making the electrolyte more concentrated.

The sulfuric acid formed in the anolyte penetrates through the membrane16 and contaminates the catolyte. The sulfuric acid lowers the pH of thecatolyte. More acidic catolyte is not desirable because the membraneloses ion selectivity between protons and copper ions. The lost of themembrane selectivity permits protons to compete with copper ions whilepenetrating the membrane, therefore, unbalancing the catolyte chemicalconcentration. To prevent the lowering of the pH of the catolyte, analkaline compound is added. Copper hydroxide consists of a copper ionsource as well as a hydroxyl source and will neutralize formed sulfuricacid, as shown by the reaction scheme (iv):Cu²⁺+2(OH)⁻+H₂SO₄→CuSO₄+2H₂O.   (iv)Therefore, schemes (iii) and (iv) are combined and the proportionalamount of copper hydroxide is added to the anolyte. The summed reactionis depicted in scheme (v), namely copper is consistently deposited whilewater and oxygen are formed as byproducts, such as:Cu(OH)₂→Cu⁰+H₂O+½O_(2(g)).   (v)

FIG. 3 shows a longitudinal sectional view of an embodiment of acartridge system 20 including a cartridge 22 containing one embodimentof shelves 24 of the invention. The shelves 24 are vertically spacedapart and extend longitudinally between input 32 and output 34. Theshelves 24 may number in a range from about 1 to about 50, thoughpreferably from about 2 to about 10. FIGS. 3 and 4A illustrate fourhorizontal substantially flat top shelves. The cartridge 22 and theshelves 24 may be made from an assortment of materials, such as plasticsor metals, including stainless steel, aluminum, titanium, nickel-coatedsteel and various alloys, amongst others.

Chemical reagents 26 are distributed across each of the shelves 24. Thechemical reagents are exposed to plating solution 28 (depicted witharrows) flowing through the cartridge 22. The plating solution 28 entersthe cartridge at least partially depleted of various chemicalcomponents, but is enriched by flowing over the chemical reagents 26contained within the cartridge 22. The enriching process includes thedissolving and/or suspending of chemical reagents 26 within the platingsolution 28. The chemical reagents 26 usually have a solid state ofmatter (e.g., powder, pellets, crystalline), but could also be a viscousliquid or a suspension. Therefore, enriched plating solution 29 emergesfrom the output 34. A progressive and consistent transformation orenrichment of the plating solution occurs as plating solution 28 flowsacross chemical reagents 26. In one example, the shelves 24 areimpermeable to liquids (e.g., metal plate with no holes or no porosity),so the plating solution 28 passes along and not through the shelves 24.In another example, the shelves 24 are permeable to liquids, such asceramic or mesh, so the plating solution 28 passes along and/or throughthe shelves 24.

Chemical reagents 26 are compounds or mixtures of compounds selected forthe process requirements of the plating solution. Plating solutionsinclude electroless plating solutions and electroplating solutions,wherein the latter is usually the anolyte or the catolyte.Electroplating systems are utilized to deposit materials such as copper,zinc, cadmium, nickel and other metals. In one preferred embodiment, theplating solution is an anolyte within an electroplating system used toplate copper.

Chemical reagents 26 useful for copper ion replenishment in a platingsolution include copper hydroxide, copper oxide, copper carbonate,copper sulfate and copper phosphate and combinations thereof, preferablycopper hydroxide. Generally, plating solutions, enriched or depleted,have a copper ion concentration in a range from about 5 g/L to about 70g/L.

Chemical reagents 26 are also used to replenish plating solutions ofother depleted compounds and ions. In one embodiment, chemical reagentsare used to control the pH of the plating solution. The pH of thesolution can be raised or lowered by adding a basic or acidic compound,respectively. Chemical reagents 26 for replenishing hydroxyl ions toincrease the pH include copper hydroxide, ammonium salts, sodiumhydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide,magnesium hydroxide, calcium hydroxide, amongst others, and combinationsthereof. Therefore, in one embodiment, copper hydroxide is used toreplenish copper ions and hydroxyl ions.

Porous material 25 is optionally placed at either or both ends of thecartridge 22 and include porous plastics, metals, ceramics, filters,frits, membranes, wool (e.g., glass or metal), packed inert media (e.g.,silica or alumina) and the like. Generally, the porous material haspores that are penetrable for enriched plating solution (suspensions),but prevents chemical reagents 26 from uncontrollably passing throughthe cartridge 22. The porous material has pores with a diameter in therange from about 10 μm to about 2,000 μm.

FIGS. 4A-C show cross-sectional views of cartridge system 20 with avariety of geometries for cartridges and shelves. FIG. 4A shows the fourflat shelves 24 of FIG. 3 as described above. FIG. 4B shows shelves withlongitudinal grooves 36. The grooves 36 further segregate the chemicalreagents 26 into various rows running along each shelf. FIG. 4C shows acylindrical cartridge 37 containing tubular shelves 38. Tubular shelves38 also hold chemical reagents 26 in segregated rows. The shelvesdistribute (i.e., provide more surface area) chemical reagents 26. Timeexposure between the plating solution and the chemical reagent variesthe degree of enrichment the plating solution endures. Therefore, theflow of the plating solution through cartridge 22 varies in a range fromabout 0.5 L/min to about 10 L/min, depending on the bath volume andperformance.

The flow of the plating solution is maintained due to part of headspace30 provided above the top surface of the chemical reagents 26.Generally, headspace 30 has a height in the range from about 1 cm toabout 50 cm, preferably from about 5 cm to about 30 cm. Headspace 30changes throughout the process with respect to time, since the chemicalreagents 26 are consumed by the plating solution and the height ofheadspace increases. Also, headspace 30 changes throughout the processwith respect to certain segments along the shelves. Besides consumption,chemical reagents 26 also migrate and erode along the shelves.

In several examples, as depicted in FIGS. 5A-C, cartridge system 20 isplaced into anolyte loops with various configurations. In oneembodiment, FIG. 5A shows cartridge system 20 placed into a singleanolyte loop. As anolyte requires replenishment of chemical reagents(e.g., Cu²⁺ or OH⁻), pump 120 draws depleted anolyte from the anolytetank 110. With control valve 130 open, pump 120 pushes the depletedanolyte through cartridge system 20. The anolyte emerges from thecartridge system 20 enriched with the specific chemical reagentsrequired for the plating process (e.g., Cu(OH)₂). Upon exiting thecartridge system 20, anolyte flows to the electroplating cell 100, wherethe plating process commences, forming depleted anolyte, which istransferred back to the anolyte tank 110. This cycle resumes as theanolyte is recirculated throughout the anolyte loop.

In another embodiment, FIG. 5B shows cartridge system 20 placed into ananolyte loop also including a bypass line. The bypass line is usefulwhen the anolyte is only partially depleted of the necessary chemicalreagents. Though depleted anolyte will contain some essential chemicalreagents, the concentration of the reagents is too low and affects theplating process. However, partially depleted anolyte is suited to berecirculated and used in the electroplating process prior to beingenriched by cartridge system 20. Depleted or partially depleted anolyteis determined per process parameters. As anolyte requires replenishmentof chemical reagents (e.g., Cu²⁺ or OH⁻), pump 120 draws depletedanolyte from the anolyte tank 110. With control valve 130 open andcontrol valve 135 closed, pump 120 pushes the depleted anolyte throughcartridge system 20. The anolyte emerges from the cartridge system 20enriched with the specific chemical reagents required for the platingprocess (e.g., Cu(OH)₂). Upon exiting the cartridge system 20, anolyteflows to the electroplating cell 100. However, with control valve 130closed and control valve 135 opened, pump 120 pushes the partiallydepleted anolyte through a bypass around the cartridge system 20 anddirectly to the electroplating cell 100. Upon the commencement of theplating process, depleted anolyte is transferred back to the anolytetank 110. This cycle resumes as the anolyte is recirculated throughoutthe anolyte loop.

The anolyte cycle system depicted in FIG. 5B has an advantage over thesystem depicted in FIG. 5A due to the cartridge bypass line, namely,more control of the supplemental chemical reagent addition. Since thesystem of FIG. 5B has the bypass line, anolyte is recirculated with theoption to pass through cartridge system 20. For any of the anolyte loopsdepicted in FIGS. 5A-C, the capacity of anolyte tank 110 can beincreased to slow the anolyte dilution from the addition of depletedanolyte coming from cell 100.

The system depicted in FIG. 5C includes several anolyte loops linkedtogether via the anolyte tank 110. One loop includes the electroplatingcell 100 in fluid communication with the anolyte tank 110. Pump 120circulates the anolyte within this loop. However, an auxiliary loop isalso linked with the anolyte tank 110. The auxiliary loop includes thecartridge system 20 connected to a control valve 134 and a pump 125. Inone aspect, pump 125 is a high-pressure pump. Also incorporated to theauxiliary loop is a bypass line managed by control valve 132. Thereforein one aspect, with control valve 134 opened and control valve 132closed, anolyte can be circulated between the anolyte tank 110 andcartridge system 20 to be enriched with chemical reagents, while theanolyte is circulated between the anolyte tank 110 and theelectroplating cell 100. In another aspect, control valve 134 is closedwhile control valve 132 is opened and cartridge system 20 does notreplenish the supplemental chemical reagents to the system.

In another embodiment, FIGS. 6A-B show cartridge 40 as a vertical vesselin which a lower portion of the interior of the vessel expands upwardlyto form an inverted conical bottom 42. The cartridge 40 includes top 39as a portion of housing 41, both made from an assortment of materials,such as plastics or metals, including stainless steel, aluminum,titanium, nickel-coated steel, various alloys amongst others.

At the base of the conical bottom 42, an injector 43 is positioned in avertical arrangement. The conical bottom 42 collects the settlingchemical reagents 26 by gravitational forces. This settling processmaintains the chemical reagents 26 in contact with the injector 43. Theinjector has an input 45 that is in fluid communication with theelectroplating system. Depleted electrolyte 28 combined with or withoutgas (e.g., air) passes through the input 45 and is introduced into thecartridge 40 through at least one output 47 of injector 43. In oneembodiment, there are multiple outputs 47 in a single injector 43. Theorifice that provides the output 47 generally has a diameter in therange from about 0.1 mm to about 1 mm. As depicted in FIG. 6B, outputs47 are less than normal (i.e., <90°) relative to the plane of the axisof the conical bottom 42. That is, the outputs 47 generally pointdownward, towards the conical bottom 42 and extend through the sides 48of injector 43. However, in one embodiment (not shown), the channels arenormal or pointing upward, but have an optional flap in order to keepchemical reagent from descending into the outputs.

Plating solution or electrolyte is administered into the cartridge 40through the injector 43. Chemical reagents 26 are disposed within thecartridge 40, so the electrolyte travels through the chemical reagents26 and into a headspace 49. An under pressure (e.g., vacuum system)and/or an over pressure (e.g., compressed gas) is utilized to assist themigration of the electrolyte through the cartridge 40. The electrolytebecomes enriched with the chemical reagents 26, (i.e., dissolved orsuspended) while passing through the cartridge 40. The enrichedelectrolyte 29 accumulates near or at the headspace 49, and thenproceeds to exit the cartridge 40 through the manifold 44. In oneembodiment, the headspace 49 has enriched anolyte 29 as well asaccumulated gas 46 or air. The accumulated gas 46 is bled from theheadspace prior or during the flow of enriched anolyte 29. In anotherembodiment, a porous material (not shown), such as sponges, porousplastics, metals, ceramics, filters, frits, membranes, wool (e.g., glassor metal), packed inert media (e.g., silica or alumina) and the alike isdisplaced below the manifold 44 to inhibit any large particulate ofchemical reagents 26 from leaving the cartridge 40.

In another embodiment, FIG. 7 shows a plating system 50 that includes acartridge 40 of the invention. The enriched electrolyte 29 is added toanolyte tank 52, which is in fluid communication with an electroplatingcell 56 and pump 58 within an anolyte loop. Anolyte is depleted ofreagent chemical (e.g., CU²⁺ and OH⁻) during the plating process withinthe electroplating cell 56. Pump 58 drives the circulation of depletedanolyte to the anolyte tank 52 and enriched anolyte from the anolytetank 52 to the electroplating cell 56.

A pH controller 54, pH sensor 57 and a computer 55 monitor and regulatethe pH of the anolyte within the anolyte tank 52. A pH controller may beselected from a variety of commercially available models, such asdTRANSpH 01 from JUMO Process Control Inc., DP24-E Process Meter fromOmega, EMIT-pH from Pathfinder Instruments, and LED pH/ORPindicator/controller from Kemko Instruments. In one embodiment, the pHis maintained in the range from about 1.0 to about 5.0, preferably, fromabout 2.0 to about 4.0 and more preferably from about 2.8 to about 3.0.In another embodiment, the pH is maintained at less than 3.4 to preventchemical precipitants (e.g., copper hydroxide) from forming and cloudingthe anolyte.

As the pH of the anolyte becomes too low, an aliquot of the anolyte istransferred from anolyte tank 52 to canister 53 via three-way valve 60.Generally, three-way valve 61 is positioned to pressurize anolyte tank52 with compressed gas (e.g., air) and three-way valve 60 is positionedas to accept the aliquot from the anolyte tank 52 to the canister 53.Once the aliquot is transferred, then both valves 60 and 61 are turnedoff. Subsequently, three way valve 61 is positioned to pressurize thecanister 53 containing the aliquot of the anolyte while three-way valve60 is positioned to permit the flow of the aliquot into the cartridge 40via the injector 43. The enriched anolyte emerges from the cartridge 40via the manifold 44 and into the anolyte tank 52. As the enrichedanolyte combines with the depleted anolyte, acidic protons areneutralized by the incoming hydroxyl ions and copper ions become moreconcentrated. In practice, the concentration of the anolyte will notvary much since control of the replenishment is occurring real time.That is, when valves 60 and 61 are timed and positioned correctly, theanolyte will reach a relatively constant pH with minimal flux (e.g.,about 0.5 pH units). The compressed gas is delivered from a source 62,such as a tank or an in-house line and may include air, N₂, Ar, He, H₂and combinations thereof.

FIG. 8 is a diagram illustrating a timing sequence of valves 60 and 61during an electroplating process useful in the plating system 50depicted in FIG. 7. The timing of valves 60 and 61 is controlled by thepH controller 54 in combination with a computer 55. The valves 60 and 61change positions every second or so and remain synchronized as describedabove. When the pH of the anolyte drops to a lower limit (LL), thecompressed gas (e.g., air) moves the electrolyte from canister 53 intocartridge 40. The time t₁ is slightly longer (e.g., about a second) thanthat required to push all of the anolyte from canister 53, so that asmall amount of air also penetrates in to the cartridge 40. The airprovides a thorough mixing of the chemical reagents with the anolyte andenriches the suspension (e.g., copper hydroxide) near the top of thecartridge 40 within headspace 49. This thorough mixing with the air andthe conical shape of the bottom of the cartridge prevents cakeformation. During time t₂, compressed air is stopped by closing valve 61and canister 53 is refilled with anolyte through valve 60. During t₃,the anolyte is injected into cartridge 40 with the timing quick enoughto prevent penetration of air into the canister 53, about a second.Canister 53 is refilled with anolyte that is subsequently injected intothe cartridge 40. Thereafter, an enriched anolyte is transferred fromthe cartridge 40 to the anolyte tank 52. This cycle continues until thepH reaches a higher limit (HL), then ceases until the pH of the anolytewithin the anolyte tank reaches the LL. The overall sequence repeatsduring the electroplating process.

In another embodiment, FIG. 9 shows a plating system 70 that includes acartridge 40. The enriched electrolyte 29 is added to anolyte tank 52,which is in fluid communication with an electroplating cell 56 and pump58 within an anolyte loop. Anolyte is depleted of reagent chemical(e.g., Cu²⁺ and OH⁻) during the plating process within theelectroplating cell 56. Pump 58 drives the circulation of depletedanolyte to the anolyte tank 52 and enriched anolyte from the anolytetank 52 to the electroplating cell 56. The depleted anolyte istemporally contained within a section 71 of the anolyte tank 52. Section71 is separated by partition 80 and will gather depleted anolyte as wellas enriched anolyte, before flowing over into the main compartment ofanolyte tank 52.

A pH controller 54, pH sensor 57 and a computer 55 monitors andregulates the pH of the anolyte within section 71. In one embodiment,the pH is maintained in the range from about 1.0 to about 5.0,preferably, from about 2.0 to about 4.0 and more preferably from about2.8 to about 3.0. In another embodiment, the pH is maintained at lessthan 3.4 to prevent chemical precipitants (e.g., copper hydroxide) fromforming and clouding the anolyte.

As the pH of the anolyte becomes too low, an aliquot of the anolyte istransferred from anolyte tank 52 to canister 53 via two-way valve 76.Pump 58 helps push the anolyte to canister 53. Once the aliquot istransferred, then two-way valve 72 is positioned to pressurize thecanister 53 containing the aliquot of the anolyte while two-way valve 78is positioned to permit the flow of the aliquot into the cartridge 40.The enriched anolyte flows from the cartridge 40 to section 71 of theanolyte tank 52. As the enriched anolyte combines with the depletedanolyte, acidic protons are neutralized by the incoming hydroxyl ionsand copper ions become more concentrated. Two-way valve 74 is positionedopen and gas flow agitates the enriched anolyte with the depleted withthe flow of gas. In practice, the concentration of the anolyte will notvary much since the replenishment is occurring in real time. That is,when valves 72, 74, 76 and 78 are timed and positioned correctly, theanolyte will reach a relatively constant pH with minimal flux (e.g.,about 0.5 pH units). The compressed gas is delivered from a source 62,such as a tank or an in-house line and may include air, N₂, Ar, He, H₂and combinations thereof.

In one embodiment depicted in FIG. 10A, injector system 82 includes aninjector 84 with output holes 85 and a cup 86 with output holes 87. Cup86 is rotatable as to line-up the output holes 85 with output holes 87.Once lined-up, anolyte will pass through holes 85 and 87 and into thecartridge. To remove cartridge 40, output holes 85 and 87 are misalignedto turn off the excess of chemical reagents 26 from escaping thecartridge 40. FIG. 10A illustrates cup 86 disposed within the injector84, while in another embodiment, FIG. 10B shows an injector 94 disposedwithin a cup 96 as part of injector system 92. Also, injector 94contains output holes 95 and cup 96 contains output holes 97. The outputholes 85 and 87 generally point horizontal while the output holes 95 and97 point in a downwardly direction.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for dispensing a chemical reagent into a platingsolution comprising: a tank for containing the plating solution; avessel in fluid communication with the tank, wherein the vessel has aninlet and an outlet; at least one horizontal shelf contained inside thevessel, wherein the at least one horizontal shelf is positioned to holdthe chemical reagent and expose the chemical reagent to the platingsolution flowing from the inlet to the outlet.
 2. The apparatus of claim1, wherein at least one horizontal shelf is impermeable to the platingsolution.
 3. The apparatus of claim 1, wherein the plating solution isan acidic, electrochemical anolyte and includes copper ions.
 4. Theapparatus of claim 3, wherein a headspace is disposed above the at leastone horizontal shelf.
 5. The apparatus of claim 4, wherein the headspaceis in a range from about 5 cm to about 30 cm.
 6. The apparatus of claim5, wherein the electrochemical anolyte flows from the inlet to theoutlet via the headspace.
 7. The apparatus of claim 6, wherein theelectrochemical anolyte is replenished by the chemical reagent.
 8. Theapparatus of claim 7, wherein the chemical reagent comprises a coppersource compound selected from the group consisting of copper hydroxide,copper carbonate, copper oxide, copper sulfate, copper phosphate andcombinations thereof.
 9. The apparatus of claim 1, wherein the at leastone horizontal shelf includes a flat shelf, a longitudinally groovedshelf, a tubular shelf or combinations thereof.
 10. The apparatus ofclaim 9, wherein the vessel comprises at least one porous materialselected from the group consisting of a membrane, a filter, a frit, amesh and combinations thereof.
 11. An apparatus for dispersing achemical reagent to a plating solution comprising: a tank for containingthe plating solution; and a vertical vessel in fluid communication withthe tank, comprising: a lower portion of the vertical vessel includingan inlet and an injector port; an upper portion of the vertical vesselincluding an outlet and a manifold; and the chemical reagent positionedbetween the inlet and the outlet.
 12. The apparatus or claim 11, whereinthe lower portion expands radially outwardly.
 13. The apparatus of claim12, wherein the injector port is positioned to direct the platingsolution in a downward direction away from the output.
 14. The apparatusof claim 11, wherein the plating solution is an acidic, electrochemicalanolyte and includes copper ions.
 15. The apparatus of claim 11, whereina headspace is disposed above the chemical reagent.
 16. The apparatus ofclaim 15, wherein the headspace is in a range from about 5 cm to about30 cm.
 17. The apparatus of claim 16, wherein the plating solution flowsfrom the inlet to the outlet via the headspace.
 18. The apparatus ofclaim 17, wherein the plating solution is replenished by the chemicalreagent.
 19. The apparatus of claim 18, wherein the chemical reagentcomprises a copper source compound selected from the group consisting ofcopper hydroxide, copper carbonate, copper oxide, copper sulfate, copperphosphate and combinations thereof.
 20. A method for replenishing copperin a plating solution comprising: flowing the plating solution from atank through an inlet of a vessel, wherein the vessel comprises achemical reagent disposed on at least one shelf; flowing the platingsolution across the chemical reagent to enrich the plating solution withthe chemical reagent; and flowing the enriched plating solution from thevessel through an outlet to the tank.
 21. The method of claim 20,wherein at least one horizontal shelf is impermeable to the platingsolution.
 22. The method of claim 20, wherein the plating solution has apH in a range from about 2.0 to about 4.0
 23. The method of claim 22,wherein a copper concentration is monitored and controlled as a functionof the pH.
 24. The method of claim 20, wherein the plating solution isan acidic, electrochemical anolyte and includes copper ions.
 25. Themethod of claim 20, wherein the plating solution flows through aheadspace disposed above the at least one shelf.
 26. The method of claim25, wherein the headspace is in a range from about 5 cm to about 30 cm.27. The method of claim 26, wherein the electrochemical anolyte flowsfrom the inlet to the outlet via the headspace.
 28. The method of claim24, wherein the chemical reagent comprises a copper source compoundselected from the group consisting of copper hydroxide, coppercarbonate, copper oxide, copper sulfate, copper phosphate andcombinations thereof.
 29. The method of claim 28, wherein the at leastone shelf includes a flat shelf, a longitudinally grooved shelf, atubular shelf or combinations thereof.
 30. The method of claim 29,wherein the horizontal vessel comprises at least one porous materialselected from the group consisting of a membrane, a filter, a frit, amesh and combinations thereof.
 31. A method for monitoring andcontrolling a pH setting of a plating solution in a tank comprising:transferring an aliquot of the plating solution to a container;pressurizing the container with a gas to transfer the aliquot to avessel, wherein the vessel comprises an injector, a chemical reagent anda manifold; passing the aliquot through the injector to enrich thealiquot with a portion of the chemical reagent; transferring theenriched aliquot through the manifold to the plating solution in thetank; determining a pH of the plating solution with a pH meter; andcomparing the pH to the pH setting and repeating the transferring of theenriched aliquot to the plating solution until the pH is equivalent tothe pH setting.
 32. The method of claim 31, wherein a copperconcentration is monitored and controlled as a function of the pHsetting.
 33. The method of claim 31, wherein the pH setting is in arange from about 2.0 to about 4.0.
 34. The method of claim 31, whereinthe plating solution is an acidic, electrochemical anolyte and includescopper ions.
 35. The method of claim 31, wherein the chemical reagentcomprises a copper source compound selected from the group consisting ofcopper hydroxide, copper carbonate, copper oxide, copper sulfate, copperphosphate and combinations thereof.
 36. An apparatus for dispensing achemical reagent into a plating solution comprising: a tank forcontaining the plating solution; a vessel in fluid communication withthe tank, wherein the vessel has an inlet and an outlet; at least oneimpermeable shelf contained inside the vessel, wherein the at least oneimpermeable shelf is positioned to hold the chemical reagent and exposethe chemical reagent to the plating solution flowing from the inlet tothe outlet.